The long-term objective of this study is to understand intergenerational transmission of tobacco-related health risks. It focuses on the role of maternal-child exposure to maternal smoking during pregnancy (SDP). There are four specific aims: 1) characterize youth smoking trajectories;2a) evaluate the strength of direct relationships between SDP and youth smoking trajectories;2b) evaluate the strength of indirect influences that entail mediation during childhood and adolescence by either the offspring's behavior problems or the mother's continued smoking;3) disentangle the influence of SDP on youth smoking trajectories from other individual, peer, and family determinants of smoking. The study develops an integrated lifespan-life course framework informing four hypotheses about the social and biological mechanisms linking mothers'smoking behavior with that of their children. The methodological approach extends and evaluates findings from previous literature. Data come from the National Longitudinal Survey of Youth 1979 (NLSY79) and the Children &Young Adults of the NLSY79 (NLSY79-CYA). Together the NLSY79 and NLSY79-CYA comprise a population-representative, biennial survey of mothers and all children born to them over an 18 year period from 1986-2004. These surveys offer rich, intergenerational data on maternal and youth substance use, child cognitive and behavioral development, and the social and biological determinants of tobacco-use at the child, family, peer and neighborhood level. We employ an autoregressive latent trajectory approach that allows us to examine causal relationships among determinants measured at different ages, while also using latent variable methods to correct for the underestimation of mediation through social and developmental pathways. PUBLIC HEALTH RELEVANCE: This study examines how intergenerational pathways in early life, childhood and adolescence shape tobacco related determinants of the health and social wellbeing of maturing adolescents and young adults.